far-ir/sub-mm photometry of high-redshift objects probes their rest-frame mid- and far-ir emission, constraining t(dust), m(dust), l(far-ir), and the sfr at early epochs. currently, rest-frame far-ir data exists only for a handful of radio galaxies and qsos at z virgul 4, for a handful of lensed qsos at moderate redshifts, and for the local examples detected by iras. the detections reported to date have only three things in common: the s/n levels are low; the calibration is uncertain; and the lack of rest-frame mid-ir data (i.e. pht-c measurements) means that temperature constraints are extremely poor. here, we propose to obtain pht-c data at 90 and 160 microns for 55 qsos with redshifts in the range 3.7 < z < 4.4, tightly constraining dust properties and determining the qso far-ir luminosity function in the early universe. our redshift criterion is commensurate with our long-term aim of obtaining high spatial resolution co(1-0) and co(2-1) maps with the 0.7- and 1.3-cm receivers of the upgraded vla. of the 55 qsos in our sample (which contains all known qsos at these redshifts), 20 have already been observed to 3-sigma levels of 5 mjy or better at 1250 microns with early ground-based mm-wave bolometers (e.g. ivison 1995) and 5 have been confirmed (with s/n > 5) as being extremely luminous in the rest-frame far-ir, suggestive of significant flux density levels (virgul50-100 mjy) in the pht-c filters. we have a parallel programme to observe this sample of qsos at wavelengths beyond 350 microns with the scuba sub-mm camera on jcmt: the combined iso, scuba and vla measurements will be crucial for our understanding of the evolution of the gas and dust content and the star-formation histories of qsos.
Instrument
PHT22
Temporal Coverage
1997-01-31T10:59:12Z/1998-01-16T19:45:39Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the world's first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
